Polyester polymer having phenolic functionality and coating compositions formed therefrom

ABSTRACT

A polyester polymer is provided that includes at least one pendant phenolic-containing group. In one embodiment, the polyester polymer is combined with an optional crosslinker and an optional carrier to form a coating composition suitable for use in coating articles such as packaging articles. The coating composition typically includes a resole phenolic crosslinker. In one embodiment, the polyester polymer has at least one phenolic-containing group that comprises an adduct of cardanol.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional of U.S. patent application Ser. No.13/133,257 (now U.S. Pat. No. 9,096,772) filed on Aug. 2, 2011, which isthe National Stage filing under 35 U.S.C. 371 of InternationalApplication No. PCT/US2009/067347 filed on Dec. 9, 2009, which claimsthe benefit of U.S. Provisional Application No. 61/121,454 filed on Dec.10, 2008, each entitled “Polyester Polymer Having Phenolic Functionalityand Coating Compositions Formed Therefrom,” each of which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

This invention relates to a polyester polymer, and coating compositionsincluding the polymer.

BACKGROUND

The application of coatings to metals to retard or inhibit corrosion iswell established. This is particularly true in the area of metal foodand beverage cans. Coatings are typically applied to the interior ofsuch containers to prevent the contents from contacting the metal of thecontainer. Contact between the metal and the packaged product can leadto corrosion of the metal container, which can contaminate the packagedproduct. This is particularly true when the contents of the containerare chemically aggressive in nature. Protective coatings are alsoapplied to the interior of food and beverage containers to preventcorrosion in the headspace of the container between the fill line of thefood product and the container lid, which is particularly problematicwith high-salt-content food products.

Packaging coatings should preferably be capable of high-speedapplication to the substrate and provide the necessary properties whenhardened to perform in this demanding end use. For example, the coatingshould be safe for food-contact; not adversely affect the taste of thepackaged food or beverage product; have excellent adhesion to thesubstrate; resist staining and other coating defects such as “popping,”“blushing” and/or “blistering;” and resist degradation over long periodsof time, even when exposed to harsh environments. In addition, thecoating should generally be capable of maintaining suitable filmintegrity during container fabrication and be capable of withstandingthe processing conditions that the container may be subjected to duringproduct packaging.

Various coatings have been used as interior protective can coatings,including epoxy-based coatings and polyvinyl-chloride-based coatings.Each of these coating types, however, has potential shortcomings. Forexample, the recycling of materials containing polyvinyl chloride orrelated halide-containing vinyl polymers can be problematic. There isalso a desire to reduce or eliminate certain epoxy compounds commonlyused to formulate food-contact epoxy coatings.

To address the aforementioned shortcomings, the packaging coatingsindustry has sought coatings based on alternative binder systems such aspolyester resin systems. It has been problematic, however, to formulatepolyester-based coatings that exhibit the required balance of coatingcharacteristics (e.g., flexibility, adhesion, corrosion resistance,stability, resistance to crazing, etc.). For example, there has been atradeoff between corrosion resistance and fabrication properties forsuch coatings. Polyester-based coatings suitable for food contact thathave exhibited both good fabrication properties and an absence ofcrazing having tended to be too soft and exhibit unsuitable corrosionresistance. Conversely, polyester-based coatings suitable for foodcontact that have exhibited good corrosion resistance have typicallyexhibited poor flexibility and unsuitable crazing when fabricated.

What is needed in the marketplace is an improved binder system for usein coatings such as packaging coatings.

SUMMARY

In one aspect, the present invention provides a binder system comprisinga polyester polymer having phenolic functionality. The polyester polymertypically includes at least one, and more preferably a plurality, ofphenolic-containing pendant and/or terminal groups. The polyesterpolymer preferably includes at least one phenolic-containing pendant (orside) group. In one embodiment, at least one of the phenolic-containinggroups is a derivative of cardanol. In another embodiment, at least oneof the phenolic-containing groups is provided by diphenolic acid, morepreferably at least one of the phenolic-containing groups is adiphenolic-acid-based pendant group.

In another aspect, the invention provides a coating composition usefulfor coating a wide variety of articles, including food or beveragecontainers. Certain preferred coating compositions of the invention areparticularly useful as food-contact coatings for use on surfaces ofmetal food or beverage containers. The coating composition typicallyincludes a phenolic-functional polyester, an optional crosslinker, andan optional carrier. In a presently preferred embodiment, the optionalcrosslinker includes at least one resole phenolic crosslinker.

In yet another aspect, the invention provides an article coated on atleast one surface with a coating composition described herein. Incertain embodiments, the coated article comprises a food or beveragecan, or a portion thereof, having a body portion and/or end portioncoated with a coating composition of the invention.

In yet another aspect, the invention provides a method for producing acoated article. The method includes providing a coating compositiondescribed herein and applying the coating composition on a substrate(typically a planar metal substrate) prior to, or after, forming thesubstrate into an article such as food or beverage can or a portionthereof.

The above summary of the present invention is not intended to describeeach disclosed embodiment or every implementation of the presentinvention. The description that follows more particularly exemplifiesillustrative embodiments. In several places throughout the application,guidance is provided through lists of examples, which examples can beused in various combinations. In each instance, the recited list servesonly as a representative group and should not be interpreted as anexclusive list.

The details of one or more embodiments of the invention are set forth inthe description below. Other features, objects, and advantages of theinvention will be apparent from the description and from the claims.

Selected Definitions

Unless otherwise specified, the following terms as used herein have themeanings provided below.

As used herein, the term “organic group” means a hydrocarbon group (withoptional elements other than carbon and hydrogen, such as oxygen,nitrogen, sulfur, and silicon) that is classified as an aliphatic group,cyclic group, or combination of aliphatic and cyclic groups (e.g.,alkaryl and aralkyl groups). The term “aliphatic group” means asaturated or unsaturated linear or branched hydrocarbon group. This termis used to encompass alkyl, alkenyl, and alkynyl groups, for example.The term “alkyl group” means a saturated linear or branched hydrocarbongroup including, for example, methyl, ethyl, isopropyl, t-butyl, heptyl,dodecyl, octadecyl, amyl, 2-ethylhexyl, and the like. The term “alkenylgroup” means an unsaturated, linear or branched hydrocarbon group withone or more carbon-carbon double bonds, such as a vinyl group. The term“cyclic group” means a closed ring hydrocarbon group that is classifiedas an alicyclic group or an aromatic group, both of which can includeheteroatoms.

A group that may be the same or different is referred to as being“independently” something. Substitution is anticipated on the organicgroups of the compounds of the present invention. As a means ofsimplifying the discussion and recitation of certain terminology usedthroughout this application, the terms “group” and “moiety” are used todifferentiate between chemical species that allow for substitution orthat may be substituted and those that do not allow or may not be sosubstituted. Thus, when the term “group” is used to describe a chemicalsubstituent, the described chemical material includes the unsubstitutedgroup and that group with O, N, Si, or S atoms, for example, in thechain (as in an alkoxy group) as well as carbonyl groups or otherconventional substitution. Where the term “moiety” is used to describe achemical compound or substituent, only an unsubstituted chemicalmaterial is intended to be included. For example, the phrase “alkylgroup” is intended to include not only pure open chain saturatedhydrocarbon alkyl substituents, such as methyl, ethyl, propyl, t-butyl,and the like, but also alkyl substituents bearing further substituentsknown in the art, such as hydroxy, alkoxy, alkylsulfonyl, halogen atoms,cyano, nitro, amino, carboxyl, etc. Thus, “alkyl group” includes ethergroups, haloalkyls, nitroalkyls, carboxyalkyls, hydroxyalkyls,sulfoalkyls, etc. On the other hand, the phrase “alkyl moiety” islimited to the inclusion of only pure open chain saturated hydrocarbonalkyl substituents, such as methyl, ethyl, propyl, t-butyl, and thelike.

When a group is defined to be “null” or a “null group” what is meant isthat the group is absent. By way of example, when a group such as, e.g.,a linking group is defined to have a structure represented by theformula —(CR^(a)R^(b))_(n)—, at least two of the R groups (e.g., atleast one R group from each of a pair of adjacent carbon atoms) willtypically be a null group if the linking group includes a carbon-carbondouble or triple bond.

The term “substantially free” of a particular mobile compound means thatthe compositions of the invention contain less than 100 parts permillion (ppm) of the recited mobile compound. The term “essentiallyfree” of a particular mobile compound means that the compositions of theinvention contain less than 10 ppm of the recited mobile compound. Theterm “essentially completely free” of a particular mobile compound meansthat the compositions of the invention contain less than 1 ppm of therecited mobile compound. The term “completely free” of a particularmobile compound means that the compositions of the invention containless than 20 parts per billion (ppb) of the recited mobile compound.

If the aforementioned phrases are used without the term “mobile” (e.g.,“substantially free of XYZ compound”) then the compositions of thepresent invention contain less than the aforementioned amount of thecompound whether the compound is mobile in the coating or bound to aconstituent of the coating.

The term “mobile” means that the compound can be extracted from thecured coating when a coating (typically ˜1 milligram per squarecentimeter (mg/cm²) (6.5 mg/in²) thick) is exposed to a test medium forsome defined set of conditions, depending on the end use. An example ofthese testing conditions is exposure of the cured coating to HPLC-gradeacetonitrile for 24 hours at 25° C.

The term “food-contact surface” refers to a surface of an article (e.g.,a food or beverage container) that is in contact with, or suitable forcontact with, a food or beverage product. When used in the context of acoating composition applied on a food-contact surface of a packagingarticle (e.g., a food or beverage container), the term refers to theunderlying substrate (typically associated with an interior surface ofthe packaging article) on which the coating composition is applied anddoes not imply that the underlying portion of the substrate will be incontact with a food or beverage product.

The term “crosslinker” refers to a molecule capable of forming acovalent linkage between polymers or between two different regions ofthe same polymer.

The term “on”, when used in the context of a coating applied on asurface or substrate, includes both coatings applied directly orindirectly to the surface or substrate. Thus, for example, a coatingapplied to a primer layer overlying a substrate constitutes a coatingapplied on the substrate.

Unless otherwise indicated, the term “polymer” includes bothhomopolymers and copolymers (i.e., polymers of two or more differentmonomers).

The term “unsaturation” when used in the context of a compound refers toa compound that includes at least one non-aromatic carbon-carbon doubleor triple bond.

The term “comprises” and variations thereof do not have a limitingmeaning where these terms appear in the description and claims.

The terms “preferred” and “preferably” refer to embodiments of theinvention that may afford certain benefits, under certain circumstances.However, other embodiments may also be preferred, under the same orother circumstances. Furthermore, the recitation of one or morepreferred embodiments does not imply that other embodiments are notuseful, and is not intended to exclude other embodiments from the scopeof the invention.

As used herein, “a,” “an,” “the,” “at least one,” and “one or more” areused interchangeably. Thus, for example, a coating composition thatcomprises “an” additive can be interpreted to mean that the coatingcomposition includes “one or more” additives.

Also herein, the recitations of numerical ranges by endpoints includeall numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, 5, etc.). Furthermore, disclosure of a range includesdisclosure of all subranges included within the broader range (e.g., 1to 5 discloses 1 to 4, 1.5 to 4.5, 1 to 2, etc.).

DETAILED DESCRIPTION

In one aspect, the invention provides a polyester polymer havingphenolic functionality. The polyester polymer preferably includes atleast one, and more preferably a plurality, of phenolic-containingpendant and/or terminal groups. Preferably, the polyester polymerincludes one or more phenolic-containing pendant groups. As used herein,the phrase “phenolic-containing group” refers to a group, typically apendant or terminal group, which (i) includes one or more phenolicgroups and (ii) may include one or more other groups. In preferredembodiments, the polyester polymer includes one or more phenolic groupscapable of entering into a crosslinking reaction with a crosslinker suchas, for example, a resole-type phenolic crosslinker.

In another aspect, the invention is a coating composition that includesthe phenolic-functional polyester. While non-food-contact coatingcompositions are within the scope of this invention, preferred coatingcompositions are packaging coating compositions suitable for use asfood-contact coatings. The coating composition of the inventionpreferably includes a phenolic-functional polyester polymer, an optionalcrosslinker (preferably a resole-type phenolic crosslinker), and anoptional liquid carrier. The coating composition preferably alsoincludes a catalyst (such as, e.g., an acid catalyst) to enhance curingand/or crosslinking Although liquid-carrier-based coating compositionsare preferred, it is contemplated that the phenolic-functional polyesterpolymer of the invention may have utility in other coating applicationtechniques such as, for example, powder coating, extrusion coating, orlamination.

Conventional food-contact, polyester-based packaging coatings havetypically been based on a mixture of a high-molecular weight polyesterpolymer and crosslinking resin. Such polyesters have typically includedrelatively few reactive hydroxyl groups and, moreover, the reactivegroups of the crosslinking resins have not typically exhibited a highpropensity to enter into crosslinking reactions with the hydroxyl groupsof the polyester. Upon curing, relatively few crosslinks are believed tobe formed between the polyester and the crosslinking resin, resulting ina network of self-crosslinked crosslinker resin having unreactedpolyester polymer dispersed therein. Such conventional polyestercoatings have suffered from a variety of performance issues such as poorchemical resistance, a lack of flexibility, and/or unsuitable crazing.As used herein, the term “crazing” refers to specific coating defectsthat occur upon fabrication of a coated metal substrate. While notintending to be bound by any theory, these coating defects are believedto be attributable to an increase in the crystallinity of coatingmaterials that occurs between curing of the coating and fabrication ofthe coated article. Unlike conventional food-contact polyester coatings,preferred cured coatings of the invention exhibit a suitable balance ofcoating properties, including excellent corrosion resistance, excellentfabrication properties, and an absence of crazing.

While not intending to be bound by any theory, the superb balance ofcoating properties exhibited by preferred coating compositions of theinvention is believed to be attributable, at least in part, to one ormore of: (i) the reactivity of the phenolic group(s) of the polyester,(ii) the locating of crosslinking sites throughout the polyester polymer(as opposed to merely at terminal ends as is typical for conventionalpolyesters) through incorporation of phenolic-containing pendant groups,(iii) an increased number of crosslinking sites in the polyesterpolymer, and/or (iv) the particular selection of crosslinker(s).

Suitable polyester polymers may be prepared using standard condensationreactions. The polyester polymer is typically derived from a mixture ofat least one polyfunctional alcohol (“polyol”) esterified with at leastone polycarboxylic acid (or derivative thereof).

Examples of suitable polycarboxylic acids include dicarboxylic acids andpolycarboxylic acids having higher acid functionality (e.g.,tricarboxylic acids, tetracarboxylic acids, etc.), precursors orderivatives thereof (e.g., an esterifiable derivative of apolycarboxylic acid, such as a dimethyl ester or anhydride), or mixturesthereof. Suitable polycarboxylic acids may include, for example, maleicacid, fumaric acid, succinic acid, adipic acid, phthalic acid,tetrahydrophthalic acid, methyltetrahydrophthalic acid,hexahydrophthalic acid, methylhexahydrophthalic acid,endomethylenetetrahydrophthalic acid, azelaic acid, sebacic acid,tetrahydrophthalic acid, isophthalic acid, trimellitic acid,terephthalic acid, a naphthalene dicarboxylic acid,cyclohexane-dicarboxylic acid, glutaric acid, dimer fatty acids,anhydrides or derivatives thereof, and mixtures thereof. If desired,adducts of polyacid compounds (e.g., triacids, tetraacids, etc.) andmonofunctional compounds may be used. An example of one such adduct ispyromellitic anhydride pre-reacted with benzyl alcohol. It should beunderstood that in synthesizing the polyester, the specified acids maybe in the form of anhydrides, esters (e.g., alkyl ester) or likeequivalent form. For sake of brevity, such compounds are referred toherein as “carboxylic acids.”

Examples of suitable polyols include diols, polyols having three or morehydroxyl groups (e.g., triols, tetraols, etc.), and combinationsthereof. Suitable polyols may include, for example, ethylene glycol,propylene glycol, 1,3-propanediol, glycerol, diethylene glycol,dipropylene glycol, triethylene glycol, trimethylolpropane,trimethylolethane, tripropylene glycol, neopentyl glycol,pentaerythritol, 1,4-butanediol, hexylene glycol, cyclohexanedimethanol,a polyethylene or polypropylene glycol, isopropylidene bis(p-phenylene-oxypropanol-2), and mixtures thereof. If desired, adductsof polyol compounds (e.g., triols, tetraols, etc.) and monofunctionalcompounds may be used. An example of one such adduct isdipentaerythritol pre-reacted with benzoic acid.

As discussed above, the polyester polymer of the invention preferablyincludes phenolic functionality. In presently preferred embodiments, thepolyester polymer includes one or more (e.g., ≥2, ≥3, ≥4, ≥5, ≥10, etc.)phenolic-containing pendant groups. The phenolic-containing pendantgroup preferably includes at least one phenolic group in which (i) oneor more of the ortho or para positions of the aromatic ring is free ornot deactivated, e.g., for purposes of an electrophilic attack or, morepreferably, (ii) where one or more of the ortho or para positions of thearomatic ring have been activated.

In preferred embodiments, the polyester polymer has at least one, morepreferably two or more, phenolic-containing pendant groups of formula(I):

where:

-   -   —[BACKBONE SEGMENT]—depicts a segment of the backbone of the        polyester polymer;    -   X, if present, depicts an organic linking group (e.g., a        divalent organic linking group) connected to the backbone;    -   Z depicts a phenolic group;    -   R¹ and R² are preferably independently selected from a hydrogen        atom, a substituted or unsubstituted alkyl group, a substituted        or unsubstituted cycloalkyl group, a substituted or        unsubstituted aryl group (including, e.g., a phenolic group), a        substituted or unsubstituted alkenyl group, or a null group        (e.g., if one or more carbon-carbon double and/or triple bonds        is present in the —(CR¹R²)_(n)— group); and    -   n is 0 or more, preferably ≥1, more preferably from about 1 to        about 30 and, in some embodiments, 1 or 2.

The (CR¹R²)_(n) group of Formula (I) is preferably attached to thearomatic ring of the Z phenolic group at a meta or para position, whichis illustrated in the below simplified structure (II):

where:

-   -   one of R⁴, R⁵, or R⁶ includes the aforementioned (CR¹R²)_(n)        group of Formula (I) and links the phenolic group to the        polyester backbone, wherein, if desired, two of R⁴, R⁵, or R⁶        can join to form a ring optionally containing one or more        heteroatoms; and    -   each of the remaining R groups (i.e., the four remaining R³-R⁷        groups that do not include the aforementioned (CR¹R²)_(n) group        of structure (II) preferably denotes one of a hydrogen atom, a        hydroxyl group, or an organic group (e.g., a substituted or        unsubstituted alkyl or cycloalkyl group, a substituted or        unsubstituted aryl group, or a substituted or unsubstituted        alkenyl group).

As depicted in structure (II), R³ and R⁷ are located at the orthopositions of the phenolic ring. The R³ and R⁷ groups are preferablyselected such that the ortho positions of the phenolic ring remainsufficiently reactive to, for example, react with a crosslinker such asa resole phenolic crosslinker Similarly, R⁴, R⁵, and R⁶ are preferablyselected such that the ortho positions of the phenolic ring remainsubstantially reactive. In presently preferred embodiments, each of R³and R⁷ is preferably independently one of a hydrogen atom, a methylolgroup, or an etherified methylol group. In one embodiment, both of R³and R⁷ are hydrogen.

X, if present, may be any suitable linking group. In some embodiments,the X group may include one or more condensation linkage groups such asan amide, urethane, ether, urea, or carbonate ester (—O—C(═O)—O—)linkage group. The condensation linkage may be attached directly to theaforementioned (CR¹R²)_(n) group of Formula (I) or, alternatively, maybe attached to another group of X that is attached to the (CR¹R²)_(n)group. Similarly, the condensation linkage may be attached directly tothe backbone of the polyester polymer or may be attached to anothergroup of X that is attached to the polymer backbone. In certainpreferred embodiments, the X group includes an ester linkage group. Insome embodiments, X is an ester group.

X may include one or more substituted or unsubstituted hydrocarbyllinkage groups. In some embodiments, a C1-C30 substituted orunsubstituted hydrocarbyl linkage group is attached on one end to thepolyester backbone and on another end to the phenolic group. In someembodiments, X may have a structure depicted by the schematic formula—C(R⁸R⁹)— , where R⁸ and R⁹ preferably independently denote a hydrogenatom, a substituted or unsubstituted alkyl group, a substituted orunsubstituted cycloalkyl group, a substituted or unsubstituted arylgroup, a substituted or unsubstituted alkenyl groups, or a null group.

In some embodiments, one of R⁸ or R⁹ is hydrogen and one of R⁸ or R⁹ isan alkyl or alkenyl group. For example, certain phenolic-functionalpolyesters made from reactants including maleinized cardanol adducts(see, for example, the maleinized cardanol adduct depicted structurallyherein) may have such an X group.

The phenolic-functional polyester polymer of the invention may includeany suitable number of phenolic-containing pendant and/or terminalgroups. As discussed above, one useful measure of such groups is thenumber of such groups present on the polymer. Another useful measure isthe weight percent of the phenolic-containing pendant groups relative tothe total weight of the phenolic-functional polyester polymer. Inpreferred embodiments, the phenolic-containing groups (more preferablypendant phenolic-containing groups) constitute between about 1 and 60weight percent (“wt-%”) of the polyester polymer. More preferably,phenolic-containing pendant groups constitute greater than about 5 wt-%,even more preferably greater than about 10 wt-%, and even morepreferably greater than about 15 wt-% of the phenolic-functionalpolyester polymer. More preferably, phenolic-containing pendant groupsconstitute less than about 40 wt-%, even more preferably less than about35 wt-%, and even more preferably less than about 30 wt-% of thephenolic-functional polyester polymer. The above wt-% for thephenolic-containing pendant group(s) is determined in the context of theweight of the monomers that include the phenolic-containing pendantgroup(s) relative to the total weight of the polymer. Thus, for example,if an oligomer having a phenolic-containing pendant group isincorporated into the backbone of the polyester polymer, the wt-% ofphenolic-containing pendant group in the polymer is calculated using theweight of the monomer that includes the phenolic-containing pendantgroup (as opposed to the weight of the oligomer that includes themonomer). In some embodiments, the aforementioned phenolic-containingpendant group amounts correspond to an amount of diphenolic acidincorporated into the polymer.

Phenolic functionality may be incorporated into the polyester polymer ofthe invention using any suitable means. For example, the phenolicfunctionality may be provided by either of the following non-limitingapproaches: (A) modifying a preformed polyester polymer to include aphenolic-containing group (preferably a phenolic-containing pendantgroup) or (B) forming a polyester polymer from a mixture of reactantsincluding one or more reactants having a phenolic group.

A non-limiting example of method (A) above includes the steps of:

-   -   1. providing a polyester polymer having reactive functional        groups (preferably one or more of which is a pendant reactive        functional group) capable of participating in a condensation        reaction such as, for example, carboxylic, hydroxyl, amine,        carbonate ester, isocyanate groups, or mixtures thereof;    -   2. providing a phenolic-containing compound have a functional        group capable of reacting with the aforementioned functional        group of the polyester polymer to form a condensation linkage        such as, for example, an ester, amide, urethane, urea, or        carbonate ester linkage; and    -   3. reacting the polyester polymer and the phenolic-containing        compound to form a polyester having phenolic functionality, and        more preferably, pendant phenolic functionality.

For the above step 2, it is contemplated that the reactive group of thephenolic-containing compound capable of reacting with the functionalgroup of the polyester polymer can be introduced into thephenolic-containing compound using a Diels-Alder reaction or Diels-enereaction. For example, a phenol-containing compound having anunsaturated substituted or unsubstituted hydrocarbyl group (e.g., analkenyl group) as a substituent of the phenol group can be reacted withan unsaturated compound having the functional group capable of reactingwith the functional group of the polyester polymer.

After the phenolic-functional polyester has been formed, it may be usedas is or it may be further reacted with formaldehyde (preferably in thepresence of butanol or a like compound) to graft methylols or etherifiedmethylols onto the phenolic ring.

The phenolic-containing groups may be derived from any suitable compoundor compounds. Examples of suitable compounds include:

alkyl esters thereof; cardanol; and mixtures or derivatives thereof. Ina presently preferred embodiment, the phenolic-group is derived fromdiphenolic acid.

Although not preferred, p-hydroxybenzoic acid may be used if desired.The generalized structure for p-hydroxybenzoic acid is provided below.

While not intending to be bound by any theory, direct linkage of acarbonyl carbon (e.g., such as present in p-hydroxybenzoic acid) to acarbon of the phenolic ring is believed to unsuitably deactivate thephenolic ring. To avoid such deactivation, phenolic-containing compoundsare preferably used that include at least one carbon atom (e.g., in theform of a methylene carbon atom) between the phenolic ring and thecarbon atom of a carbonyl group or other reactive functional group.

By way of example, a phenolic-functional polyester of the invention maybe formed by reacting pHPAA, pHPPA, diphenolic acid, and/or alkyl estersthereof with a trifunctional or higher polyol such as trimethylolpropane (“TMP”) prior to, or after, incorporating the trifunctional orhigher polyol into the backbone of a polyester polymer via acondensation reaction.

Similarly, by way of example, a phenolic-functional polyester of theinvention may also be formed by reacting (i) a phenolic-containingcompound having a hydroxyl group or other group reactive with an acid,anhydride, or ester group (e.g., hydroxyl phenyl ethanol) with (ii) anacid, anhydride, or ester-functional branching compound (e.g.,trimellitic anhydride) preferably having at least three groups reactivewith a hydroxyl group (with an anhydride group being counted as twogroups) prior to, or after, incorporating the branching compound intothe backbone of a polyester polymer via a condensation linkage.

In some embodiments, the phenolic-functional polyester polymer of theinvention is derived from a phenol compound having an unsaturatedhydrocarbyl chain (which may be substituted) such as an alkenyl- oralkynyl-substituted phenol containing one or more carbon-carbon doubleor triple bonds. To facilitate incorporation into a polyester, acompound having one or more reactive groups (e.g., hydroxyl, carboxylic,amine, isocyanate, etc.) may be grafted on to the unsaturatedhydrocarbyl chain of the phenol-containing compound.

Cardanol is a presently preferred alkenyl-substituted phenol. Cardanolis a meta-substituted phenol derived from cashew nut shell liquid. Ageneralized structure of cardanol is provided below:

where n corresponds to the number of carbon-carbon double bonds presentin the alkenyl side chain and is typically 0, 1, 2 or 3. When more thanone carbon-carbon double bond is present in the meta-positioned alkenylchain, the carbon-carbon double bonds may be conjugated ornon-conjugated. Since cardanol is derived from a naturally occurringfeedstock, commercial feedstocks of cardanol may contain variants of theabove generalized structure (e.g., compounds having a second hydroxylgroup at the “open” meta position) and minor amounts of other compounds.It is contemplated that compounds having the above generalized structuremay be reacted on the alkenyl chain without affecting significantly thebeneficial reactive properties of the phenolic ring. In addition, it isalso contemplated that the phenolic ring itself may be furthersubstituted, if desired.

The unsaturation present on the side chain of cardanol may be utilizedfor purposes of grafting cardanol onto a preformed unsaturated polyesteror onto another ingredient useful for forming the polyester polymer. Byway of example, cardanol may be grafted onto an unsaturated reactantsuch as an unsaturated polyol, an unsaturated polycarboxylic acid oranhydride, or any other unsaturated compound having suitable reactivityto form a grafted cardanol adduct capable of being polymerized (e.g.,via a condensation reaction such as esterification) into the backbone ofthe polyester polymer. Any suitable grafting mechanism may be used toproduce the grafted adduct or graft polymer, including mechanisms suchas Diels-Alder or Diels-ene addition reactions.

A presently preferred cardanol adduct is a reaction product of cardanoland an unsaturated anhydride. Suitable unsaturated anhydrides mayinclude unsaturated dicarboxylic acid anhydrides such as maleicanhydride, itaconic anhydride, nonenylsuccinic anhydride, citraconicanhydride, and mixtures thereof. The production of a cardanol adductfrom (a) a cardanol compound having a single carbon-carbon double bondin the alkenyl chain and, thus, an “n” of 1 and (b) maleic anhydride isillustrated below:

In embodiments where the polyester polymer includes cardanol, thepolyester polymer may include any suitable amount of cardanol to achievethe desired result. In certain embodiments, the polyester polymerincludes from about 5 to about 75% by weight of cardanol, morepreferably from about 10 to about 60% by weight of cardanol, and evenmore preferably from about 25 to about 45% by weight of cardanol.

It is further contemplated that other substituted phenolics containingside-chain unsaturation may be employed in place of, or in addition to,cardanol. Such compounds preferably include at least one phenolic grouphaving a structure pursuant to the aforementioned structure (II). Thephenolic group may be substituted with any suitable unsaturated groupthat includes at least one carbon-carbon double or triple bond and atleast two carbon atoms. For example, the unsaturated group may be aC2-C30 substituted or unsubstituted alkenyl or cycloalkenyl group havingone or more carbon-carbon double or triple bonds (e.g., 2, 3, 4, ormore). When two or more carbon-carbon double or triple bonds arepresent, the bonds may be conjugated or non-conjugated.

In some embodiments, the backbone of the polyester polymer ishydroxy-terminated or carboxy-terminated, more preferablyhydroxy-terminated.

The polyester polymer may have any suitable hydroxyl number. Hydroxylnumbers are typically expressed as milligrams of potassium hydroxide(KOH) equivalent to the hydroxyl content of 1 gram of thehydroxyl-containing substance. Methods for determining hydroxyl numbersare well known in the art. See, for example, ASTM D 1957-86 (Reapproved2001) entitled “Standard Test Method for Hydroxyl Value of Fatty Oilsand Acids” and available from the American Society for Testing andMaterials International of West Conshohocken, Pa. In certain preferredembodiments, the polyester polymer has a hydroxyl number of from 0 toabout 150, more preferably from about 10 to about 150, even morepreferably from about 25 to about 100, and optimally from about 30 toabout 80.

The polyester polymer may have any suitable acid number. Acid numbersare typically expressed as milligrams of KOH required to titrate a 1gram sample to a specified end point. Methods for determining acidnumbers are well known in the art. See, for example, ASTM D 974-04entitled “Standard Test Method for Acid and Base Number byColor-Indicator Titration” and available from the American Society forTesting and Materials International of West Conshohocken, Pa. In certainpreferred embodiments, the polyester polymer has an acid number of lessthan about 20, more preferably less than about 10, and even morepreferably less than about 5.

The molecular weight of the phenolic-functional polyester polymer of theinvention can vary depending upon material choice and the desired enduse. In preferred embodiments, the polyester polymer has a numberaverage molecular weight (Mn) of at least about 1,000, more preferablyat least about 1,500, and even more preferably at least about 3,000.Preferably, the Mn of the polyester polymer is less than about 20,000,more preferably less than about 15,000, and even more preferably lessthan about 10,000.

The phenolic-functional polyester polymer of the invention can have anysuitable glass transition temperature (Tg). Preferably, thephenolic-functional polyester exhibits a Tg of at least 0° C., morepreferably at least 5° C., and even more preferably at least 10° C. Insome embodiments, it may be desirable for the phenolic-functionalpolyester to have a Tg of less than 100° C., more preferably less than80° C., and even more preferably less than 60° C.

In some embodiments, the phenolic-functional polyester preferably has aTg greater than 60° C. For example, in some embodiments (intended forcertain end uses) where diphenolic acid is used to incorporate pendantphenolic functionality into the polyester, the phenolic-functionalpolyester preferably has a Tg greater than 60° C.

Coating compositions of the invention may include any suitable amount ofphenolic-functional polyester polymer to produce the desired result. Inpreferred embodiments, the coating compositions include at least about10, more preferably at least about 15, and even more preferably at leastabout 20 wt-% of phenolic-functional polyester polymer, based on thetotal nonvolatile weight of the coating composition. Preferably, thecoating compositions include less than about 90, more preferably lessthan about 85, and even more preferably less than about 80 wt-% ofphenolic-functional polyester polymer, based on the total nonvolatileweight of the coating composition.

If water dispersibility is desired, the phenolic-functional polyesterpolymer may contain a suitable amount of salt-containing and/orsalt-forming groups to facilitate preparation of an aqueous dispersionor solution. Suitable salt-forming groups may include neutralizablegroups such as acidic or basic groups. At least a portion of thesalt-forming groups may be neutralized to form salt groups useful fordispersing the polyester polymer into an aqueous carrier. Acidic orbasic salt-forming groups may be introduced into the polyester polymerby any suitable method.

In some embodiments, a water-dispersible phenolic-functional polymer isachieved through inclusion of a sufficient number of carboxylic acidgroups in the polymer. Examples of suitable materials for incorporatingsuch groups into the polymer include polyanhydrides such astetrahydrophthalic anhydride, pyromellitic anhydride, succinicanhydride, trimilletic anhydride (“TMA”), and mixtures thereof. In oneembodiment, a hydroxyl-terminated polyester polymer or oligomer havingone or more pendant hydroxyl groups is reacted with an anhydride such asTMA to produce a hydroxyl-terminated polyester having carboxylicfunctionality. The conditions of the reaction are controlled, includingthe temperature, to avoid gelling. The resulting carboxylic-functionalpolyester oligomer or polymer is neutralized (e.g., using a base such asan amine) to produce an aqueous dispersion. In some embodiments, it iscontemplated that water dispersibility may be provided through use ofacid-functional ethylenically unsaturated monomers that have beengrafted onto the polyester to form a polyester-acrylic copolymer,whereby a suitable number of the acid-functional groups are neutralizedwith base (such as, e.g., a tertiary amine) to produce salt groups. Seefor example, U.S. Pat. App. No. 20050196629 for examples of suchtechniques.

Preferred polyester polymers and/or coating compositions of theinventions are preferably substantially free, more preferablyessentially free, even more preferably essentially completely free, andoptimally completely free of mobile bisphenol A (BPA) and aromaticglycidyl ether compounds (e.g., diglycidyl ethers of bisphenol (BADGE),diglycidyl ethers of bisphenol F (BFDGE), and epoxy novalacs). Incertain preferred embodiments, the polyester polymer and/or coatingcomposition of the inventions are preferably substantially free, morepreferably essentially free, even more preferably essentially completelyfree, and optimally completely free of bound BPA and aromatic glycidylether compounds (e.g., BADGE, BFDGE and epoxy novalacs).

Preferred phenolic-functional polyesters are at least substantially“epoxy-free”, more preferably “epoxy-free.” The term “epoxy-free”, whenused herein in the context of a polymer, refers to a polymer that doesnot include any “epoxy backbone segments” (i.e., segments formed fromreaction of an epoxy group and a group reactive with an epoxy group).Thus, for example, a polymer made from ingredients including an epoxyresin would not be considered epoxy-free. Similarly, a polymer havingbackbone segments that are the reaction product of a bisphenol (e.g.,bisphenol A, bisphenol F, bisphenol S, 4,4′ dihydroxy bisphenol, etc.)and a halohdyrin (e.g., epichlorohydrin) would not be consideredepoxy-free. However, a vinyl polymer formed from vinyl monomers and/oroligomers that include an epoxy moiety (e.g., glycidyl methacrylate)would be considered epoxy-free because the vinyl polymer would be freeof epoxy backbone segments. In some embodiments, the coating compositionof the invention is epoxy-free, or at least substantially epoxy-free.

When present, the concentration of one or more optional crosslinkers mayvary depending upon the desired result. For example, in someembodiments, the coating compositions may contain from about 0.01 wt-%to about 40 wt-%, more preferably from about 0.5 wt-% to about 35 wt-%,or even more preferably from about 3 wt-% to about 30 wt-% of one ormore crosslinkers, by weight of nonvolatile material in the coatingcomposition.

Any suitable crosslinker can be used. For example, phenolic crosslinkers(e.g., phenoplasts), amino crosslinkers (e.g., aminoplasts), blockedisocyanate crosslinkers, materials including oxirane groups (e.g.,oxirane-functional polyester such as glycidol-modified polyesters oroxirane-functional vinyl polymers such as acrylic resins formed usingglycidyl methacrylate) and combinations thereof, may be used. Preferredcrosslinkers are at least substantially free, more preferably completelyfree, of bound BPA and aromatic glycidyl ethers. See, e.g., PCTapplication number PCT/US2009/065467 for a discussion of methods forproducing glycidol-modified polyesters.

Examples of suitable phenolic crosslinkers (e.g., phenoplasts) includethe reaction products of aldehydes with phenols. Formaldehyde andacetaldehyde are preferred aldehydes. Examples of suitable phenols thatcan be employed include phenol, cresol, p-phenylphenol,p-tert-butylphenol, p-tert-amylphenol, cyclopentylphenol, cresylic acid,BPA (not presently preferred), and combinations thereof.

Resole-type phenolic crosslinkers are presently preferred for food orbeverage coating applications and, in particular, food-contact coatings.While not intending to be bound by any theory, cured packaging coatingsformulated using the phenolic-functional polyester polymer of theinvention and one or more resole-type phenolic crosslinkers (with orwithout additional crosslinkers such as, e.g., aminoplasts and/orblocked isocyanate) have been observed to exhibit superior coatingproperties (e.g., superior corrosion resistance) relative to comparablecoating compositions formulated with other types of crosslinker(s)(e.g., amino and/or blocked isocyanate alone without resole-typephenolic crosslinkers). In preferred embodiments, the resole-typephenolic crosslinker is believed to form covalent bonds with thephenolic groups of the polyester, resulting in the formation of acrosslinked polymer network including both the phenolic crosslinker andthe polyester. While not intending to be bound by any theory, this isbelieved to be responsible, at least in part, for the enhanced coatingproperties exhibited by certain preferred packaging coatings of theinvention relative to conventional packaging coatings containingpolyester and phenolic resins that do not form such a polymer networkwith each other.

Examples of suitable resole phenolic crosslinkers include the DUREZ33160 and 33162 products (each available from Durez Corporation,Addison, Tex.), the Bakelite 6535 and 6470 products (each available fromHexion Specialty Chemicals GmbH), the PHENODUR PR 285 and PR 812products (each available from CYTEC Surface Specialties, Smyrna, Ga.),and the SFC 112 and 142 products (each available from the SI Group,previously Schenectady) and mixtures thereof. In presently preferredembodiments, the coating composition includes, on a total solids basis,at least about 5, more preferably at least about 10, and even morepreferably at least about 15% by weight of resole phenolic crosslinkers.

Amino crosslinker resins (e.g., aminoplasts) are typically thecondensation products of aldehydes (e.g., such as formaldehyde,acetaldehyde, crotonaldehyde, and benzaldehyde) with amino- oramido-group-containing substances (e.g., urea, melamine andbenzoguanamine). Suitable amino crosslinking resins include, forexample, benzoguanamine-formaldehyde-based resins,melamine-formaldehyde-based resins (e.g., hexamethonymethyl melamine),etherified melamine-formaldehyde, urea-formaldehyde-based resins, andmixtures thereof.

Condensation products of other amines and amides can also be employedsuch as, for example, aldehyde condensates of triazines, diazines,triazoles, guanadines, guanamines and alkyl- and aryl-substitutedmelamines. Some examples of such compounds are N,N′-dimethyl urea,benzourea, dicyandimide, formaguanamine, acetoguanamine, glycoluril,ammelin 2-chloro-4,6-diamino-1,3,5-triazine,6-methyl-2,4-diamino-1,3,5-triazine, 3,5-diaminotriazole,triaminopyrimidine, 2-mercapto-4,6-diaminopyrimidine,3,4,6-tris(ethylamino)-1,3,5-triazine, and the like. While the aldehydeemployed is typically formaldehyde, other similar condensation productscan be made from other aldehydes, such as acetaldehyde, crotonaldehyde,acrolein, benzaldehyde, furfural, glyoxal and the like, and mixturesthereof.

Suitable commercially available amino crosslinking resins include, forexample, CYMEL 301, CYMEL 303, CYMEL 370, CYMEL 373, CYMEL 1131, CYMEL1125, and CYMEL 5010 Maprenal MF 980 (all available from CytecIndustries Inc., West Patterson, N.J.) and Uramex BF 892 (available fromDSM, Netherlands).

One preferred optional ingredient is a catalyst to increase the rate ofcure and/or the extent of crosslinking The catalyst is typically chosenfrom among the catalysts known for use in the crosslinking of resoletype phenolic resin and/or the electrophilic substitution of aromaticrings. Examples of such catalysts, include but are not limited to,strong acids (e.g., dodecylbenzene sulphonic acid (DDBSA), available asCYCAT 600 from Cytec), methane sulfonic acid (MSA), p-toluene sulfonicacid (pTSA), dinonylnaphthalene disulfonic acid (DNNDSA), and triflicacid, phosphoric acid, and mixtures thereof.

If used, a catalyst is preferably present in an amount of at least 0.01wt-%, and more preferably at least 0.1 wt-%, based on the weight ofnonvolatile material. If used, a catalyst is preferably present in anamount of no greater than 3 wt-%, and more preferably no greater than 1wt-%, based on the weight of nonvolatile material.

If desired, coating compositions of the invention may optionally includeother additives that do not adversely affect the coating composition ora cured coating resulting therefrom. The optional additives arepreferably at least substantially free of mobile and/or bound BPA andaromatic glycidyl ether compounds (e.g., BADGE, BFDGE and epoxy novalaccompounds) and are more preferably completely free of such compounds.Suitable additives include, for example, those that improve theprocessability or manufacturability of the composition, enhancecomposition aesthetics, or improve a particular functional property orcharacteristic of the coating composition or the cured compositionresulting therefrom, such as adhesion to a substrate. Additives that maybe included are carriers, additional polymers, emulsifiers, pigments,metal powders or paste, fillers, anti-migration aids, anti-microbials,extenders, curing agents, lubricants, coalescents, wetting agents,biocides, plasticizers, crosslinking agents, antifoaming agents,colorants, waxes, anti-oxidants, anticorrosion agents, flow controlagents, thixotropic agents, dispersants, adhesion promoters, UVstabilizers, scavenger agents or combinations thereof. Each optionalingredient can be included in a sufficient amount to serve its intendedpurpose, but preferably not in such an amount to adversely affect acoating composition or a cured coating resulting therefrom.

Any suitable carrier may be used to prepare coating compositions of theinvention. Suitable carriers include carrier liquids such as organicsolvents, water, and mixtures thereof. Suitable organic solvents includealiphatic hydrocarbons (e.g. mineral spirits, kerosene, high flashpointVM&P naptha, and the like); aromatic hydrocarbons (e.g. benzene,toluene, xylene, solvent naphtha 100, 150, 200 and the like); alcohols(e.g. ethanol. n-propanol, isopropanol, n-butanol, iso-butanol and thelike); ketones (e.g. acetone, 2-butanone, cyclohexanone, methyl arylketones, ethyl aryl ketones, methyl isoamyl ketones, and the like);esters (e.g. ethyl acetate, butyl acetate and the like); glycols (e.g.butyl glycol), glycol ethers (e.g. ethylene glycol monomethyl ether,ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,propylene glycol monomethyl ether, and the like); glycol esters (e.g.butyl glycol acetate, methoxypropyl acetate and the like); and mixturesthereof. Preferably, the liquid carrier(s) are selected to provide adispersion or solution of the polyester polymer of the invention forfurther formulation.

In some embodiments, the coating composition of the invention is awater-based varnish. In some such embodiments, preferably at least about50 wt-% of the liquid carrier system is water, more preferably about 60wt-% is water, and even more preferably about 75 wt-% is water. Certaincoating compositions of the invention include at least about 10 wt-% ofwater, more preferably at least about 20 wt-% of water, and even morepreferably at least about 40 wt-% of water (in some embodiments about 50wt-% or more of water), based on the total weight of the coatingcomposition.

Coating compositions of the invention may be prepared by conventionalmethods in various ways. For example, the coating compositions may beprepared by simply admixing the phenolic-functional polyester polymer,optional crosslinker and any other optional ingredients, in any desiredorder, with sufficient agitation. The resulting mixture may be admixeduntil all the composition ingredients are substantially homogeneouslyblended. Alternatively, the coating compositions may be prepared as aliquid solution or dispersion by admixing an optional carrier liquid,the phenolic-functional polyester polymer, optional crosslinker, and anyother optional ingredients, in any desired order, with sufficientagitation. An additional amount of carrier liquid may be added to thecoating compositions to adjust the amount of nonvolatile material in thecoating composition to a desired level.

The total amount of solids present in coating compositions of theinvention may vary depending upon a variety of factors including, forexample, the desired method of application. Presently preferred coatingcompositions include at least about 30, more preferably at least about35, and even more preferably at least about 40 wt-% of solids, based onthe total weight of the coating composition. Preferably, the coatingcompositions include less than about 80, more preferably less than about70, and even more preferably less than about 65 wt-% of solids, based onthe total weight of the coating composition.

In another embodiment, the invention provides a coating composition thatincludes the phenolic-functional polyester polymer of the invention incombination with an optional thermoplastic dispersion and optionalcrosslinker. Such coating compositions may be suitable for variousapplications such as, for example, food or beverage packagingapplications. While not intending to be bound by any theory, it isbelieved that certain phenolic-functional polyester polymers of theinvention are capable of stabilizing certain thermoplastic materialssuch as, for example, poly vinyl chloride (“PVC”) to prevent or decreasedegradation of the thermoplastic material or a cured coating resultingtherefrom. Thus, it is within the scope of this invention to include anefficacious amount of the polyester polymer of the invention (e.g., forpurposes of stabilizing the thermoplastic dispersion) in an organosol orplastisol coating composition. Organosols useful in the compositions ofthe invention, include, for example, vinyl organosols. A “vinylorganosol,” as used herein, is a dispersion of vinyl chloride polymers(preferably high-molecular-weight vinyl chloride polymers) in a liquidcarrier. A discussion of suitable materials and preparation methods forsuch compositions may be found, for example, in U.S. Pat. App. No.PCT/US2008/058899.

Organosol coating compositions of the invention preferably include atleast about 10, more preferably at least about 15, and even morepreferably at least about 20 wt-% of phenolic-functional polyesterpolymer of the invention, based on the total nonvolatile weight of thecoating composition. The organosol coating compositions preferablyinclude less than about 90, more preferably less than about 70, and evenmore preferably less than about 60 wt-% of phenolic-functional polyesterpolymer, based on the total nonvolatile weight of the coatingcomposition.

Organosol coating compositions of the invention preferably include atleast about 10, more preferably at least about 15, and even morepreferably at least about 20 wt-% of thermoplastic material, based onthe total nonvolatile weight of the coating composition. The organosolcoating compositions preferably include less than about 80, morepreferably less than about 70, and even more preferably less than about65 wt-% of thermoplastic material, based on the total nonvolatile weightof the coating composition.

When present in an organosol composition of the present invention, theconcentration of one or more optional crosslinkers may vary dependingupon the desired result. For example, in some embodiments, the coatingcomposition may contain one or more crosslinkers in an amount ofpreferably at least about 0.5, more preferably at least about 1, andeven more preferably at least about 1.5 wt-%, by weight of nonvolatilematerial in the coating composition. The amount of one or more optionalcrosslinkers included in the coating composition is preferably less thanabout 15, more preferably less than about 4.5, and even more preferablyless than about 2 wt-%, by weight of nonvolatile material in the coatingcomposition.

Examples of suitable thermoplastic materials include halogenatedpolyolefins, which include, for example, copolymers and homopolymers ofvinyl chloride, vinylidenefluoride, polychloroprene, polychloroisoprene,polychlorobutylene, and combinations thereof. PVC is a particularlypreferred thermoplastic material. The thermoplastic material preferablyhas a number average molecular weight (Mn) of from about 40,000 to about300,000; more preferably from about 75,000 to about 200,000; and evenmore preferably from about 100,000 to about 150,000.

In applications involving packaging coatings, dispersion gradethermoplastic particles are preferred, where the particles range in sizefrom greater than 0 to about 5 microns, based on volume-average medianparticle diameter. Other sizes, however, can be used such as, forexample, non-dispersion grade thermoplastic particles that range in sizefrom about 5 to about 100 microns, based on volume-average medianparticle diameter.

The thermoplastic material is preferably dispersed in a liquid carrierto form a thermoplastic dispersion. Examples of suitable liquid carriersinclude an organic solvent, a plasticizer, or mixtures thereof. Suitableorganic solvents may include polar solvents such as ketones (e.g., MIBKand DIBK), glycol ethers, alcohols, aliphatic hydrocarbons, aromatichydrocarbons, or mixtures thereof. In some embodiments, it may beadvantageous to choose a solvent that has an affinity to thethermoplastic material and/or one that can swell the thermoplasticparticles to facilitate storage stability of the liquid coatingcomposition. Preferred liquid carriers exhibit sufficient volatility tosubstantially evaporate from the coating composition during the curingprocess.

Cured coatings of the invention preferably adhere well to metal (e.g.,steel, tin-free steel (TFS), tin plate, electrolytic tin plate (ETP),aluminum, etc.) and provide high levels of resistance to corrosion ordegradation that may be caused by prolonged exposure to products such asfood or beverage products. The coatings may be applied to any suitablesurface, including inside surfaces of containers, outside surfaces ofcontainers, container ends, and combinations thereof.

The coating composition of the invention can be applied to a substrateusing any suitable procedure such as spray coating, roll coating, coilcoating, curtain coating, immersion coating, meniscus coating, kisscoating, blade coating, knife coating, dip coating, slot coating, slidecoating, and the like, as well as other types of premetered coating. Inone embodiment where the coating is used to coat metal sheets or coils,the coating can be applied by roll coating.

The coating composition can be applied on a substrate prior to, orafter, forming the substrate into an article. In some embodiments, atleast a portion of a planar substrate is coated with one or more layersof the coating composition of the invention, which is then cured beforethe substrate is formed into an article.

After applying the coating composition onto a substrate, the compositioncan be cured using a variety of processes, including, for example, ovenbaking by either conventional or convectional methods. The curingprocess may be performed in either discrete or combined steps. Forexample, the coated substrate can be dried at ambient temperature toleave the coating composition in a largely un-crosslinked state. Thecoated substrate can then be heated to fully cure the coatingcomposition. In certain instances, the coating composition can be driedand cured in one step. In preferred embodiments, the coating compositionof the invention is a heat-curable coating composition.

The curing process may be performed at any suitable temperature,including, for example, temperatures in the range of about 180° C. toabout 250° C. If metal coil is the substrate to be coated, curing of theapplied coating composition may be conducted, for example, by subjectingthe coated metal to a temperature of about 230° C. to about 250° C. forabout 15 to 30 seconds. If metal sheeting is the substrate to be coated(e.g., such as used to make three-piece food cans), curing of theapplied coating composition may be conducted, for example, by subjectingthe coated metal to a temperature of about 190° C. to about 210° C. forabout 8 to about 12 minutes.

Coating compositions of the invention may be useful in a variety ofcoating applications. The coating compositions are particularly usefulas adherent coatings on interior or exterior surfaces of metalcontainers. Examples of such articles include closures (including, e.g.,internal surfaces of twist off caps for food and beverage containers);internal crowns; two- and three-piece cans (including, e.g., food andbeverage containers); shallow drawn cans; deep drawn cans (including,e.g., multi-stage draw and redraw food cans); can ends (including, e.g.,easy open can ends); monobloc aerosol containers; and general industrialcontainers, cans, and can ends.

Preferred coating compositions of the invention are particularly suitedfor use on interior or exterior surfaces of metal food or beveragecontainers, including food-contact surfaces. Preferably, the curedcoatings are retortable when employed in food and beverage containerapplications. Preferred cured coatings of the invention are capable ofwithstanding elevated temperature conditions frequently associated withretort processes or other food or beverage preservation or sterilizationprocesses. Particularly preferred cured coatings exhibit enhancedresistance to such conditions while in contact with food or beverageproducts that exhibit one or more aggressive (or corrosive) chemicalproperties under such conditions. Examples of such aggressive food orbeverage products may include meat-based products, milk-based products,fruit-based products, energy drinks, and acidic or acidified products.

The coating composition of the invention is particularly suitable foruse as a coating on the food-contact surface of the sidewall of athree-piece food can. The coating composition is typically applied to ametal sheet which is then typically cured prior to fabricating thecoated sheet into the sidewall of a three-piece food can.

Test Methods

Unless indicated otherwise, the following test methods were utilized inthe Examples that follow.

A. Solvent Resistance Test

The extent of “cure” or crosslinking of a coating is measured as aresistance to solvents, such as methyl ethyl ketone (MEK) or isopropylalcohol (IPA). This test is performed as described in ASTM D 5402-93.The number of double rubs (i.e., one back-and-forth motion) is reported.Preferably, the MEK solvent resistance is at least 30 double rubs. Theresults of this test for coatings prepared according to the presentinvention are presented in Tables 4, 7 and 8.

B. Adhesion Test

Adhesion testing was performed to assess whether the coatingcompositions adhere to the coated substrate. The Adhesion Test wasperformed according to ASTM D 3359-Test Method B, using SCOTCH 610 tape,available from 3M Company of Saint Paul, Minn. Adhesion is generallyrated on a scale of 0-10 where a rating of “10” indicates no adhesionfailure, a rating of “9” indicates 90% of the coating remains adhered, arating of “8” indicates 80% of the coating remains adhered, and so on. Acoating is considered herein to satisfy the Adhesion Test if it exhibitsan adhesion rating of at least 8. The results of this test for coatingsprepared according to the present invention (after retort pursuant tothe Retort Method) are presented in Tables 4 and 7.

C. Blush Resistance Test

Blush resistance measures the ability of a coating to resist attack byvarious solutions. Typically, blush is measured by the amount of waterabsorbed into a coated film. When the film absorbs water, it generallybecomes cloudy or looks white. Blush was measured visually using a scaleof 0-5 where a rating of “0” indicates no blush, a rating of “1”indicates slight whitening of the film, and a rating of “3” indicateswhitening of the film, and so on. Blush ratings of “2” or less aretypically desired for commercial packaging coatings and optimally “1” orless. The results of this test for coatings prepared according to thepresent invention are presented in Tables 4, 7 and 8.

D1. Process or Retort Resistance Test

This is a measure of the coating integrity of the coated substrate afterexposure to heat and pressure with a liquid such as water. Retortperformance is not necessarily required for all food and beveragecoatings, but is desirable for some product types that are packed underretort conditions. The procedure is similar to the Sterilizations orPasteurization Test. Testing is accomplished by subjecting the substrateto heat ranging from 105-130° C. and pressure ranging from 0.7 kg/cm²(kilograms per square centimeter) to 1.05 kg/cm² for a period of 15 to90 minutes. The coated substrate was then tested for adhesion and blushas described above. In food or beverage applications requiring retortperformance, adhesion ratings of 10 and blush ratings of at least 7 aretypically desired for commercially viable coatings. The results of thistest for coatings prepared according to the present invention arepresented in Tables 4, 7 and 8.

D2. Retort Method

This test provides an indication of an ability of a coating to withstandconditions frequently associated with food or beverage preservation orsterilization. For the present evaluation, coated substrate samples (inthe form of ETP flat panels) were placed in a vessel and partiallyimmersed in a test substance. While totally immersed in the testsubstance, the coated substrate samples were placed in an autoclave andsubjected to heat of 130° C. and pressure of 1 atm above atmosphericpressure for a time period of 60 minutes. Just after retort, the coatedsubstrate samples were tested for adhesion, blush resistance, and/orstain resistance.

The test substances of Tables 4, 7 and 8 below were prepared usingdeionized water having the weight percent of the listed materialdissolved therein.

E. Wedge Bend Test

This test provides an indication of a level of flexibility of a coatingand an extent of cure. For the present evaluation, test wedges wereformed from coated rectangular metal test sheets (which measured 12 cmlong by 5 cm wide). Test wedges were formed from the coated sheets byfolding (i.e., bending) the sheets around a mandrel. To accomplish this,the mandrel was positioned on the coated sheets so that it was orientedparallel to, and equidistant from, the 12 cm edges of the sheets. Theresulting test wedges had a 6 mm wedge diameter and a length of 12 cm.To assess the wedge bend properties of the coatings, the test wedgeswere positioned lengthwise in a metal block of a wedge bend tester and a2.4 kg weight was dropped onto the test wedges from a height of 60 cm.

The deformed test wedges were then immersed in a copper sulphate testsolution (prepared by combining 20 parts of CuSO₄.5H₂O, 70 parts ofdeionized water, and 10 parts of hydrochloric acid (36%)) for about 2minutes. The exposed metal was examined under a microscope and themillimeters of coating failure along the deformation axis of the testwedges was measured.

The results of this test for coatings prepared according to the presentinvention are presented in Table 5, with the data expressed as a wedgebend percentage using the following calculation:100%×[(120 mm)−(mm of failure)]/(120 mm).

A mono-coat coating system is considered herein to satisfy the WedgeBend Test if it exhibits a wedge bend percentage of 70% or more.

A coating is considered herein to satisfy the Wedge Bend Test if itexhibits a wedge bend percentage of 70% or more.

EXAMPLES

The invention is illustrated by the following examples. It is to beunderstood that the particular examples, materials, amounts, andprocedures are to be interpreted broadly in accordance with the scopeand spirit of the inventions as set forth herein. Unless otherwiseindicated, all parts and percentages are by weight and all molecularweights are weight average molecular weight. Unless otherwise specified,all chemicals used are commercially available from, for example,Sigma-Aldrich, St. Louis, Mo.

Examples 1 and 2 Cardanol Adducts

TABLE 1 Example 1 Example 2 Ingredient (wt-%) (wt-%) 1 Cardanol 1500 - 166.1 69.6 2 Maleic anhydride 18.5 17.0 3 Hydroquinone mono methyl ether0.1 0.1 4 Xylene 5.2 8.1 5 Xylene 6.6 5.2

Adducts of cardanol and maleic anhydride were produced as follows. Thelist of ingredients used to produce the adducts of Examples 1 and 2 areprovided in Table 1. The cardanol compound (i.e., ingredient 1) was theCardanol 1500-1 product from Cardolite Corporation. For each of Examples1 and 2, ingredients 1-4 of Table 1 were combined, and the adducts ofcardanol and maleic anhydride were obtained by via an Adler-ene reactionby heating the resulting mixture at 180 to 200° C., under solventreflux. Formation of the adduct was followed by monitoring the amount ofunreacted maleic anhydride using gel permeation chromatography (“GPC”)analysis. The reaction was determined to be complete when the wt-% ofmaleic anhydride was less than 0.5%. The reaction time varied from about4 to about 10 hours, depending upon the recipe. The resulting mixtureswere thinned with ingredient 5. The mixture of Example 1 had anon-volatile content (“NVC”) of 88% and a measured acid value of 171.The mixture of Example 2 has a non-volatile content of 87% and ameasured acid number of 117.

Examples 3 and 4 Cardanol-Containing, Phenolic-Functional Polyester

TABLE 2 Example 3 Example 4 Ingredients (wt-%) (wt-%) 1 Neopentyl glycol28 19 2 Ethylene glycol 3 3 1-4,cyclohexane dimethanol 11 4 Benzylicalcohol 2 5 Isophthalic acid 26 20 6 Terephthalic acid 20 7 CardanolAdduct of Example 1 46 25 8 Dibutyl tin dilaurate (DBTL) 0.08 0.08 Totalreactants, % in weight 100 100 9 Xylene 9.5 10 Solvesso 100 9.3 19.4

In Examples 3 and 4, a phenolic-functional polyester was produced inwhich pendant phenolic groups were provided through incorporation of acardanol/maleic anhydride adduct into the backbone of the polyester. Theingredients for producing the phenolic-functional polyesters of Examples3 and 4 are provided in Table 2. Components 1 to 8 were reacted in areactor under reflux conditions using components 9 and/or 10. Theesterification reaction proceeded under reaction temperatures of about190 to 210° C. until an acid value of less than 10 was observed. Thefinal acid value for the polyester of Example 3 was 10 and the finalacid value of the polyester of Example 4 was 7.

The resulting resin compositions were then thinned using additionalorganic solvent. After thinning, the resin composition of Example 3 wasdetermined to constitute 70% by weight of nonvolatile material and theresin composition of Example 4 was determined to constitute 57% byweight of nonvolatile material.

Example 5 Methylolated Phenolic-Functional Polyester

Methylol groups were provided on the phenolic-containing groups of thepolyester of Example 3 using the following procedure. The ingredientsused for the methylolation process to produce the polyester of Example 5are listed in Table 3. Paraformaldehyde was reacted under basicconditions using the triethylamine (3) with butanol (1) on a molarratio, at 90° C., during 1 hour after clarification of the medium, toachieve acetal formation. The resulting mixture was then reacted withthe polyester of Example 3 in an amount such that the molar ratio ofphenolic groups to formaldehyde was about 1 to about 2.6. The pH wasadjusted to about 7.5 by adding triethylamine (5) and then butanol (6).The reaction temperature was maintained for about 3 hours at 90° C. tocomplete methylolation. Then toluene (7) was added and the temperaturewas progressively increased in order to maintain a continuous reflux.Thanks to a trap the water was eliminated while the solvent was returnedto the reactor. The reaction temperature reached about 130 to 140° C. atthe end of the process. When the viscosity (measured using the Fallingball method, 25° C.) was about 30-33 Poises, the product was cooled inorder to stop the reaction. The resulting product was 58 wt-% NVM(non-volatile material).

TABLE 3 Ingredients of Example 5 Wt-% 1 Butanol 11 2 Paraformaldehyde4.5 3 Triethylamine 0.14 4 Example 3 polyester at 70% NVM 73 5Triethylamine 1 6 Butanol 6.7 7 Toluene 2.5

Examples 6-8 Coating Compositions

The resin mixtures of Examples 3 and 5 were formulated into the coatingcompositions of Example 6, 7, and 8 by combining the resin mixtures asshown in Table 4 with resole phenolic crosslinker resin and catalyst.The resulting varnishes were bar coated at a film weight of 5-7 g/m²onto ETP 2.8/2.8 sheets (i.e., ETP sheets having a tin weight on eachside of the sheet of 2.8 g/m²). The coated sheets were cured for 12minutes in a 200° C. oven. For sake of comparison, an ETP sheet was alsocoated and cured in a similar manner with Comparative Example A, whichwas a conventional solvent-based polyester/phenolic coating compositionthat was a mixture of a high molecular weight hydroxyl-terminatedpolyester and phenolic resin, where the polyester did not includephenolic-functional groups.

The cured coated samples were then subjected to a variety of tests toassess the coating performance properties of the cured coatings ofExamples 6-8 and Comparative Example A. The results of these tests areprovided in the lower half of Table 4.

TABLE 4 Compara- tive Example Example Example Example Ingredient (wt-%*)6 7 8 A Example 3 (70% NVC) 61.8 64.2 Example 5 (58% NVC) 66.88 BAKELITE6470 resole 15.71 13.05 phenolic crosslinker (72% NVC) DUREZ 33160resole 18.12 phenolic crosslinker (60% NVC) Phosphoric Acid 85% 0.120.12 0.12 Butylglycol 19.96 19.97 19.95 TESTING DAT Number of MEK double50 100 100 100 rubs Wedge bend, % OK   74%   66%   66%   95% Tap WaterRetort** 0/100% 0/100% 0/100% 0/100% (1 hr at 130° C.) 2% Acetic AcidRetort** 2/100% 2/100% 2/100% 2/100% (1 hr at 130° C.) 1% Lactic AcidRetort* 2/100% 2/100%  4/0%  5/0% (1 hr at 130° C.) *The wt-% isindicated as a percentage of the total weight of the varnish. **Theretort data is reported as X/Y % where X is the blush on a 0 to 5 scalewith 0 being no blush and 5 being extreme blush, and Y is the % adhesionon a 0% to 100% scale with 0% being complete loss of adhesion and 100%being no detectable loss of adhesion.

Example 9 pHPAA-Containing Phenolic-Functional Polyester

Using the methods described below, the phenolic-functional polyester ofExample 9 was produced using an adduct of p-hydroxyphenyl acetic acid(“pHPAA”) and trimethylol proprane (“TMP”) to provide pendantphenolic-containing groups. The adduct was produced using theingredients listed in Table 5. TMP and pHPAA were reacted on a molarratio using a classical esterification reaction using DBTL as a catalystuntil the acid value was less than 2. The final reaction temperature wasabout 230° C. The resulting composition was thinned with xylene andSolvesso 100 solvent.

TABLE 5 Ingredient Wt-% 1 Trimethylol propane 47 2 pHydro phenyl aceticacid (pHPAA) 53 3 Dibutyl tin dilaurate (DBTL) 0.1 Total reactants, % inweight 100 4 Xylene 3 5 SOLVESSO 100 solvent 7 NVM 90 Total, % in weight100

The phenolic-functional polyester of Example 9 was produced using theingredients listed in Table 6, which include the aforementionedTMP/pHPAA phenol-diol adduct. Incorporation of the phenol-diol adductinto a polyester backbone was accomplished using classicalesterification conducted, at reflux temperatures, using ingredient 7.The reaction temperature was between about 220 and about 230° C. Thereaction was allowed to continue until the acid value was determined tobe less than 10. The resulting resin product was then thinned iningredients 8 through 11 and after thinning constituted 48.6 wt-% NVM.

TABLE 6 Wt-% of total reactants Ingredient (A2SR1733) 1 Neopentyl glycol22.5 2 Monoethylene glycol 4 3 Example 9 Phenol-diol adduct 20 4Isophthalic acid 26.75 5 Terephthalic acid 26.75 6 Dibutyl tin dilaurate(DBTL) 0.08 Total reactants; % by weight 100 7 SOLVESSO 100 solvent 2.58 Xylene 11.4 9 SOLVESSO 100 solvent 20.4 10 Butyl glycol 11.4 11Butanol 5.7 Total % by weight 100

Examples 10 and 11 Coating Compositions

The phenolic-functional polyester of Example 9 was formulated to producethe coating compositions of Examples 10 and 11. The ingredients forcoating compositions 10 and 11 are provided in Table 7. The coatingcompositions of Examples 10 and 11, as well as Comparative Example A,were applied to ETP substrate using the methods previously described forExamples 6-8. The cured coated samples were subjected to a variety oftests to assess the coating performance properties of the cured coatingsof Examples 9 and 10 relative to Comparative Example A. The results ofthese tests are provided in the lower half of Table 7.

TABLE 7 Example Example Comparative Ingredient (wt-%*) 10 11 Example AExample 9 Resin (48.6% NVC) 66.44 68.37 DUREZ 33160 resole 13.46phenolic (60% NVC) BAKELITE 6470 resole 11.55 phenolic(72% NVC)Phosphoric acid 85% 0.12 0.10 Butyl glycol 19.98 19.98 Number of MEKdouble rubs 95 100 100 TESTING DATA Wedge bend, % OK   75%   63%   95%Tap Water Retort** 0/100% 0/100% 0/100% (1 hour at 130° C.) 2% AceticAcid Retort** 1/100% 3/100% 2/100% (1 hour at 130° C.) 1% Lactic AcidRetort** 1/100% 2/100%  5/0% (1 hour at 130° C.) 2% NaCl Retort**  1/90%1.5/100%   (1 hour at 130° C.) *The wt-% is indicated as a percentage ofthe total weight of the varnish. **The coating performance data isreported using the same format as that of Table 4.

Examples 12 and 13 Organosol Coating Compositions

The phenolic-functional polyester of Example 9 was formulated to producethe organosol coating compositions of Examples 12 and 13. Theingredients for the organosol coating compositions 12 and 13 areprovided in Table 8. The organosol coating is prepared in the followingway: A dispersion of the PVC in a mixture of Solvesso 100 solvent andethyldiglycol (“EDG”) was made under high speed stirring for 30 minutes,with the temperature maintained below 30° C. The dispersion gauge waschecked with a Hegmann gauge (<6). This dispersion was added understirring at a temperature of less than 30° C. to a pre-mix of polyesterresin, phenolic resin, phosphoric acid, and butylglycol.

The coating compositions of Examples 12 and 13 were applied to ETPsubstrate using the methods previously described for Examples 6-8. Thecoated panels were cured for 10 minutes in a 200° C. oven. The curedcoated samples were subjected to a variety of tests, which wereconducted at least 24 hours after curing, to assess the coatingperformance properties of the cured coatings of Examples 12 and 13. Theresults of these tests are provided in the lower half of Table 8.

TABLE 8 Ingredient (wt-%*) Example 12 Example 13 Example 9 Resin (48.6%NVC) 25.37 19.40 DUREZ 33160 resole phenolic (60% NVC) 5.15 3.94Phosphoric acid (85%) 0.03 0.02 Butyl glycol 7.94 6.08 GEON 178 PVC30.75 35.28 Solvesso 100 15.38 17.64 EDG 15.38 17.64 TESTING DATA Numberof MEK double rubs 95 95 Wedge bend, % OK   87%   85% Tap Water Retort**(1 hour at 130° C.) 2/100% 2/100% 2% Acetic Acid Retort** (1 hour at130° C.) 2/100% 2/100% 1% Lactic Acid Retort** (1 hour at 130° C.)2/100% 2/100% 2% NaCl Retort** (1 hour at 130° C.) 3/100% 3/100% *Thewt-% is indicated as a percentage of the total weight of the varnish.**The coating performance data is reported using the same format as thatof Table 4.

Example 14 Diphenolic-Acid-Containing, Phenolic-Functional Polyester

Using the methods described below, a phenolic-functional polyester wasproduced using diphenolic acid.

An adduct was first prepared as follows between 1.0 mole of trimethylolpropane and 1.01 mole of diphenolic acid (4,4-Bis(4-hydroxyphenyl)valeric acid). To a 4-neck round-bottom flask equippedwith a mechanical stirrer, a Dean-Starke trap, a condenser, athermocouple connected to a temperature control device, and an inlet fora nitrogen blanket, was added 1,024.8 parts of diphenolic acid, 475.2parts of trimethylol propane, and 1.5 parts of Fastcat 4201 (dibutyltinoxide). This mixture was heated slowly to 210° C. over the course of 300minutes. After heating another 120 minutes, the batch had an acid numberof 0.9 and a hydroxyl number of 535. The mixture was cooled to 160° C.and discharged. The solid material was broken up into small pieces foruse in the next reaction.

The phenolic-functional polyester of Example 14 was produced using theabove diphenolic acid adduct as follows. To a 4 neck round-bottom flaskequipped with a mechanical stirrer, a packed column, Dean-Starke trap, acondenser, a thermocouple connected to a temperature control device, andan inlet for a nitrogen blanket, was added 98.5 parts of neopentylglycol, 17.5 parts of ethylene glycol, 115 parts of terphthalic acid,and 0.5 parts of Fastcat 4201 (dibutyltin oxide). This mixture washeated to 220° C. over the course of 60 minutes. After heating another120 minutes, the batch had an acid number of 0.0 and a hydroxyl numberof 246. The mixture was cooled to 160° C. 9 parts of neopentyl glycol,115 parts of isophthalic acid, 18.5 parts of dimer fatty acid (Radiacid960), and 135.5 parts of the above diphenolic acid adduct were added tothe reaction mixture. The batch was heated to 220° C. over the course of90 minutes. After heating an additional 120 minutes, the batch hadbecome clear and had an acid number of 34.5. The batch was cooled to150° C. and the packed column was removed. 25 parts of xylene wereadded, and the batch was set up for reflux and heated to 205° C. andheld for 210 minutes until an acid number of 2.0 was reached. The batchwas then cooled to 180° C. at which time a mixture of 170 parts ofAromatic 100 solvent and 75 parts of xylene was added. When thisaddition was complete and the batch was no higher than 150° C., amixture of 65 parts butylcellosolve and 45 parts dibasic ester wasadded. The batch was mixed until uniform and the batch was discharged.The percent solids of the composition were 54.0%.

Example 15 Coating Composition

A finish was made from 100 parts of the phenolic-functional polyesterprepared in Example 14, 19.3 parts of BKS 7590 thermosetting phenolic(commercially available from Georgia Pacific), and 0.73 parts of a 10%H₃PO₄ solution in butanol. This finish was applied to tin free steel andtinplate and baked 10 minutes in a 400° F. (204° C.) oven to obtain adry film thickness of 4.0-5.0 milligrams/square inch. The same was donewith a leading commercial solvent-based epoxy phenolic coatingcomposition (hereinafter Comparative Example B) in the metal foodpacking industry. 202 can ends were fabricated from these panels, andthe center of the can end was subjected to a 14 inch-pound reverseimpact. These ends were sealed in cans that were hot filled at 180° F.(82° C.) with sauerkraut and ketchup (separately). The cans were put ina 120° F. (49° C.) hot room for 2 weeks. At this time the cans wereopened and the can ends were evaluated for the performance of thecoating. The results are shown in Table 9. It can be seen from Table 9that the coating from Example 3 is equivalent in performance to theindustry standard epoxy coating.

TABLE 9 ETP Substrate TFS Substrate Packed Comparative ExampleComparative Example Product Test Example B 15 Example B 15 KetchupAdhesion/ 10/10  9/10 10/10 10/10 Blush Stain/ 10/10 10/10 10/10 10/9 Corrosion Sauer- Adhesion/ 10/10 10/10 10/10 10/10 kraut Blush Stain/8/9 9/9 10/9   10/10* Corrosion *Slight countersink splitting wasobserved.

Example 16 Water-Dispersible Phenolic-Functional Polyester

A water-dispersible phenolic-functional polyester was produced asdescribed below. A phenolic-functional polyester was first produced fromthe ingredients listed below in Table 10 using the methods of Examples 3and 4. The resulting polyester had a viscosity of 44 Poises (Noury, 25°C.), an acid value of 2.6, and an NVC of 62% (theoretical value).

TABLE 10 Ingredient Amount (Weight Parts) Neopentylglycol 281.4 Ethyleneglycol 83.4 Cyclohexane dimethanol 472 Isophthalic acid 325.2Terephthalic acid 325.2 Cyclohexane dicarboxylic acid 240.2 Adduct 2(see Ex 2, Table 1) 672.6 Dibutyl tin dilaurate (DBTL) 2.4 Xylene 140.2Butylglycol 1206.7

To render the phenolic-functional polyester water dispersible, it wasreacted with an acrylic monomer mixture containing acid-functionalmonomers. The resulting copolymer was then reacted with an amine anddiluted with water to form an aqueous dispersion of the copolymer. Theingredients used in this reaction are listed below in Table 11.

TABLE 11 Ingredient Amount (Weight Parts) 1 Phenolic-FunctionalPolyester 600 of Table 10 2 Butanol 41.4 3 Styrene 23.8 4 Ethyleacrylate 7.93 5 Butyl methacrylate 10.58 6 Acrylic acid 13.93 7Methyacrylic acid 33.29 8 Benzoyl peroxide 3.38 9 Di (tamylperoxy)cyclohexane 1.68 10 Di (t amylperoxy)cyclohexane 1.68 11Dimethylethanolamine 51.7 12 Water 51.7 13 Water 490.6 14 Water 694.7

Components 1 and 2 were placed into a round-bottom flask equipped with atotal condenser and a stirrer. Under nitrogen bubbling, the mixture isheated at 120 to 122° C. Then a premix of components 2 through 8 isadded at 120 to 122° C. over 90 minutes. After 30 minutes, component 9was added and 1 hour later component 10 was added. The product was keptfor an additional hour at 120 to 122° C. and then cooled down to 100 to105° C. At 100 to 105° C., a premix of components 11 and 12 was addedover 10 minutes under agitation. Over 30 minutes, component 13 was addedand the temperature naturally decreased to 80 to 85° C. Component 14 wasadded over 30 minutes under agitation. The resulting polyester-acrylatecopolymer mixture had a Noury viscosity (25° C., Afnor 4) of 31 seconds,a pH of 8.78, an NVC of 23% (theoretical), and a volume average particlesize of 0.35 microns.

Example 17 Water-Based Coating Compositions

The water-based coating composition of Example 17 was produced from theaqueous dispersion of Example 16 and included about 80% by weight solidsof the aqueous dispersion of Example 16, about 20% by weight solids ofDUREZ 33160 phenolic resin, and 0.15% by weight of a NACURE 5925catalyst solution at 20% in butanol. The coating composition wasprepared by mixing the aforementioned ingredients at a temperature ofless than 35° C. over 30 minutes. If necessary, the viscosity wasadjusted with water to achieve a viscosity of between 60 and 75 secondsas determined by a #4 Ford Cup at 20° C.

After a minimum of 24 hours, the coating composition was applied on ETP2.8/2.8 sheets at a dry film weight of about 5-6 g/m² (grams per squaremeter) and cured for 10 minutes in a 200-205° C. oven. The cured coatingof Example 17 showed excellent adhesion to the ETP substrate. Table 12below includes the results of various coating property tests that wereconducted on the cured coating samples of Example 17. The evaluation wasconducted in comparison with an epoxy phenolic coated and cured insimilar conditions (“Comparative Example C”).

TABLE 12 Coating Property Tests Solvent Blush after Retort (1 hour at130° C.) Resistance Wedge- 2% 3% (# of Bend Acetic Lactic Coating doublerubs) (% OK) Water Acid Acid Example 80 71% 0 1 (slight 3 (slight 17micro micro blistering; blistering; excellent very good adhesion)adhesion) Compara- 100 81% 0 3 (slight 3 (slight tive* micro microExample blistering; blistering; C acceptable no adhesion) adhesion)*Comparative Example C is a commercial water-based epoxy coating forfood packaging containers.

The complete disclosure of all patents, patent applications, andpublications, and electronically available material cited herein areincorporated by reference. The foregoing detailed description andexamples have been given for clarity of understanding only. Nounnecessary limitations are to be understood therefrom. The invention isnot limited to the exact details shown and described, for variationsobvious to one skilled in the art will be included within the inventiondefined by the claims.

What is claimed is:
 1. An article, the article comprising a food orbeverage can, or portion thereof, comprising: one or more of a can bodyportion or a can end portion comprising a metal substrate; and a curedcoating present on the metal substrate, wherein the cured coating isprepared from a liquid coating composition comprising: aphenolic-functional polyester having one or more phenolic-containingpendant groups, wherein the phenolic-containing pendant groups areprovided via a condensation reaction of an acid-functionalphenolic-containing compound or an alkyl ester thereof with: (i)trifunctional or higher polyol to provide a phenolic-functional compoundor a phenolic-functional adduct that is then reacted to form thephenolic-functional polyester or (ii) a hydroxyl group structural unitderived from a trifunctional or higher polyol present in a backbone ofthe polyester polymer via a condensation reaction; and a liquid carrier.2. The article of claim 1, or portion thereof, wherein thephenolic-functional polyester includes a plurality ofphenolic-containing pendant groups.
 3. The article of claim 1, orportion thereof, wherein the phenolic-containing pendant group iscapable of entering into a crosslinking reaction with a resole-typephenolic crosslinker.
 4. The article of claim 3, or portion thereof,wherein the coating composition includes a resole-type phenoliccrosslinker.
 5. The article of claim 1, or portion thereof, wherein thecoating composition includes a crosslinker.
 6. The article of claim 5,or portion thereof, wherein the crosslinker is a resole-type phenoliccrosslinker.
 7. The article of claim 5, or portion thereof, wherein thecrosslinker comprises an aminoplast crosslinker, a blocked isocyanatecrosslinker, or a mixture thereof.
 8. The article of claim 1, or portionthereof, wherein the cured coating is present on an interior of the foodor beverage can.
 9. The article of claim 1, or portion thereof, whereinthe phenolic-functional compound comprises p-hydroxphenyl acetic acid,p-hydroxypropinoic acid, diphenolic acid, alkyl esters thereof, or amixture or derivative thereof.
 10. The article of claim 1, or portionthereof, wherein the phenolic-functional compound comprises diphenolicacid.
 11. The article of claim 1, or portion thereof, wherein thephenolic-containing pendant group is not derived from p-hydroxybenzoicacid.
 12. The article of claim 1, or portion thereof, wherein coatingcomposition includes at least 10 weight percent of the polyesterpolymer, based on the total nonvolatile weight of the coatingcomposition.
 13. The article of claim 1, or portion thereof, wherein aphenolic group of the phenolic-containing pendant group includes amethylol group, an etherified methylol group, or a combination thereof,which is attached at a para or ortho position of the phenolic ring. 14.The article of claim 1, or portion thereof, wherein thephenolic-containing pendant group constitutes from about 10 to about 60weight percent of the polyester polymer.
 15. The article of claim 1, orportion thereof, wherein the coating composition is substantially freeof bound bisphenol A and aromatic glycidyl ether compounds.
 16. Thearticle of claim 1, wherein the trifunctional or higher polyol comprisestrimethylol propane.
 17. The article of claim 1, wherein thephenolic-functional polyester polymer has a number average molecularweight of at least 3,000 and a glass transition temperature of at least10° C.
 18. The article of claim 17, wherein the coating compositionincludes at least 15% by weight of the phenolic-functional polyesterpolymer, based on the total nonvolatile weight of the coatingcomposition.
 19. An article, the article comprising a food or beveragecan, or portion thereof, comprising: a body portion or an end portioncomprising a metal substrate; and a cured coating present on the metalsubstrate on an interior of the food or beverage can or portion thereof,wherein the cured coating is prepared from a liquid coating compositioncomprising: a phenolic-functional polyester polymer having one or morephenolic-containing pendant groups, wherein the phenolic-functionalpolyester polymer is a reaction product of ingredients includingp-hydroxphenyl acetic acid, p-hydroxypropinoic acid, diphenolic acid,alkyl esters thereof, or a mixture or derivative thereof; a resole-typephenolic crosslinker; and a liquid carrier.
 20. The article of claim 19,or portion thereof, wherein a phenolic group of the phenolic-functionalpolyester polymer includes a methylol group, an etherified methylolgroup, or a combination or derivative thereof, which is attached at apara or ortho position of the phenolic ring.
 21. The article of claim19, wherein the phenolic-functional polyester polymer has a numberaverage molecular weight of at least 3,000 and a glass transitiontemperature of at least 10° C.
 22. The article of claim 19, wherein aphenolic-containing pendant group is incorporated into the polyester viareaction of p-hydroxphenyl acetic acid, p-hydroxypropinoic acid,diphenolic acid, alkyl esters thereof, or a mixture or derivativethereof, with a trifunctional or higher polyol, wherein thephenolic-containing pendant groups are provided via a reaction of anacid-functional phenolic-containing compound or an alkyl ester thereofwith: (i) a trifunctional or higher polyol to provide aphenolic-functional compound or a phenolic-functional adduct that isthen reacted to form the phenolic-functional polyester or (ii) ahydroxyl group structural unit derived from a trifunctional or higherpolyol present in a backbone of the polyester polymer.
 23. The articleof claim 22, wherein the trifunctional or higher polyol comprisestrimethylol propane.
 24. An article, the article comprising a food orbeverage can, or portion thereof, comprising: one or more of a can bodyportion or a can end portion comprising a metal substrate; and a curedcoating present on the metal substrate, wherein the cured coating isprepared from a liquid coating composition comprising: aphenolic-functional polyester having one or more phenolic-containingpendant groups, wherein the phenolic-containing pendant groups areprovided via a condensation reaction of an acid-functionalphenolic-containing compound or an alkyl ester thereof with: (i) atrifunctional or higher polyol to provide a phenolic-functional compoundor a phenolic-functional adduct that is then reacted to form thephenolic-functional polyester or (ii) a hydroxyl group structural unitderived from a trifunctional or higher polyol present in a backbone ofthe polyester polymer via a condensation reaction, and wherein aphenolic group of the phenolic-containing pendant group includes amethylol group, an etherified methylol group, or a combination thereof,which is attached at a para or ortho position of the phenolic ring; anda liquid carrier.
 25. An article, the article comprising a food orbeverage can, or portion thereof, comprising: a body portion or an endportion comprising a metal substrate; and a cured coating present on themetal substrate on an interior of the food or beverage can or portionthereof, wherein the cured coating is prepared from a liquid coatingcomposition comprising: a phenolic-functional polyester polymer havingone or more phenolic-containing pendant groups, wherein thephenolic-functional polyester polymer is a reaction product ofingredients including p-hydroxphenyl acetic acid, p-hydroxypropinoicacid, diphenolic acid, alkyl esters thereof, or a mixture or derivativethereof and wherein a phenolic group of the phenolic-functionalpolyester polymer includes a methylol group, an etherified methylolgroup, or a combination or derivative thereof, which is attached at apara or ortho position of the phenolic ring; a resole-type phenoliccrosslinker; and a liquid carrier.